The present invention relates to a heat exchanger core comprising a fluid passage member within which a fluid flows and outside of which another fluid flows and fin members formed thereon for promoting the heat exchange between the two fluids, and more particularly to a heat exchanger core whose fluid passage member is made of an aluminum-base alloy and whose fin members serve as sacrificial anodes as well for protecting the fluid passage member from corrosion.
Generally, in a heat exchanger core for use in air-cooled heat exchangers, a hot fluid flows within the heat exchanger core and air is made to flow outside of the heat exchanger core for the purpose of cooling. In the case where the heat exchange core is made of an aluminum-base alloy and is assembled by brazing, one or both members of the fluid passage member and the fin members are made of a brazing sheet. The brazing sheet comprises a core metal layer made of aluminum or corrosion-resistant aluminum alloy, and a cladding metal layer made of Al-Si-base alloy or Al-Si-Mg-base alloy, which is formed on the core metal layer.
In the case where the fluid passage member of the heat exchanger core is made of such a brazing sheet, and the fin members are made of aluminum or corrosion-resistant aluminum alloy, considerable corrosion of the heat exchanger core occurs when the air-cooled side of the heat exchanger core is exposed to a corrosive atmosphere. Therefore, the application of such air-cooled heat exchanger is significantly limited. In other words, in the conventional heat exchanger, a soldered fillet portion between the fluid passage member and the fin members becomes a cathode, while the fluid passage member itself becomes an anode and a corrosion-current flows from the fluid passage member to the fillet portion, so that the fluid passage member is corroded.